1. Field of the Invention
The present invention relates to a portable terminal, and more particularly to an antenna apparatus for a sliding-type portable terminal.
2. Description of the Related Art
In general, a “portable terminal” refers to an apparatus which a user can carry with him to perform wireless communication with a desired partner. Portable terminals are classified as either bar-type terminals, flip-type terminals, or folder-type terminals according to their appearance. The bar-type terminals have a single housing shaped like a bar. The flip-type terminals have a flip or a cover which is rotatably coupled to a bar-shaped housing by a hinge device. The folder-type terminals have a folder which is connected to a single bar-shaped housing by a hinge device in such a manner that the folder can be rotated to be folded on or unfolded from the housing.
Portable terminals may also be classified into rotation-type terminals and sliding-type terminals according to ways of opening and closing the terminals. In the rotation-type terminals, two housings are connected to each other in such a manner that one housing is rotated to be opened or closed relative to the other while they face each other. In the sliding-type terminals, one of their two housings is slid along a longitudinal direction to be opened or closed relative to the other while they face other. These variously classified portable terminals can be easily understood by those skilled in the art.
Portable terminals are equipped with an antenna apparatus to guarantee the quality of signals which are transmitted to and received from base stations and repeaters for mobile communication.
More specifically, portable terminals are conventionally equipped with an antenna apparatus which is a combination of a helical antenna and a rod antenna. The helical antenna is operated only in a region having a good radio environment. The rod antenna normally retracts in the terminals and, if necessary, extends out of the terminals for service.
Conventional antenna apparatuses are mounted on terminals in such a manner that they protrude out of the terminals. This is a hindrance to the diversified design of terminals and limits portability. In addition, the antenna apparatuses may be easily fractured by an external shock (e.g., when dropped).
For these reasons, research is currently being performed to develop an embedded antenna which is positioned within the terminals. Some manufacturers of portable terminals have already commercialized terminals which are equipped with such an embedded antenna.
However, the embedded antenna has a problem in that it has a decreased gain compared with conventional antennas which protrude out of the terminals. In the case of sliding-type terminals wherein one of a pair of the terminal housings slides and passes over the other in a speech mode, any one of the housings acts as a ground surface for the embedded antenna apparatus. This further decreases the performance of the antenna apparatus.